1. Field of the Invention
This invention relates to methods of producing a novel bioavailable modified animal feed and expanding ethanol production, and a novel bioavailable modified animal, preferably cattle, feed.
2. Description of the Background Art
Within the new Energy Bill is a Renewable Fuels Standard requiring renewable fuel production of 7.5 billion gallons by 2012. This increase from the current level of 3.8 billion gallons of ethanol will almost certainly take place by increasing the amount of ethanol produced from corn, specifically from dry-milling of corn. Dry milling of corn is the most cost effective way to increase the production of ethanol, and produces the fewest and lowest volume of by-products.
Over 11 billion bushels of corn were harvested in 2005; however, only approximately 2.6 billion bushels were processed by wet or dry milling, with only approximately 1.4 billion bushels processed for ethanol production. The remaining 8.4 billion bushels of corn are utilized mainly as animal feed, with over 2 billion bushels as cattle or dairy feed. Corn is fed to provide an inexpensive energy and protein source to feeder and dairy cattle; however, the starch in corn is readily metabolized by the rumen microorganisms. These organisms ferment the starch to organic acids, which at high concentrations can lead to acidosis in the cattle. Based on research completed by ADM Alliance Nutrition, approximately 550 million bushels could be diverted from use as cattle or dairy feed to ethanol, if a >60% digestible corn replacement could be produced. If the 550 million bushels of corn were to be diverted to produce ethanol by dry milling, an additional 1.5 billion gallons of ethanol could be produced. Based on a current production of 3.8 billion gallons of ethanol in 2006, this would increase the total ethanol production by 40% without increasing corn acreage planted.
The present invention provides for several cost effective ways that facilitate the expansion of ethanol dry mill corn refineries while maintaining adequate cattle feed supplies to the market. This invention also outlines new approaches to processing corn in dry mills. Part of the plan to maintain cattle feed supplies includes treating various biomass fiber sources to increase the digestibility for cattle, to provide a corn replacement pellet.
By diverting this corn from cattle feed to ethanol production, two issues will arise. The first issue is the loss of energy from starch for cattle feed, and the second is the additional production of corn dry milling byproducts, which will greatly over-saturate the animal feed market. Both of these issues can be addressed by upgrading the dry milling by-products to an enhanced cattle feed to replace the energy from starch.
To replace the estimated 550 million bushels of corn which could be diverted annually from dairy and beef cattle feed, an equivalent amount of bio-available feed would need to be substituted for the corn. The 550 million bushels of corn are equivalent to 26.4 billion pounds total, comprising approximately 19.6 billion pounds of starch, and 3.09 billion pounds of lignocellulosics. By the current dry milling process, 550 million bushels of corn would yield 9.2 billion pounds of distillers dried grains (DDG) and distillers dried grains with solubles (DDGS), which are the major by-products of the dry-milling process. Therefore, an additional 17.2 billion pounds of similarly bio-available feed would need to be made up by currently available lignocellulosics, such as soybeans hulls, corn stover, or wheat straw. The energy content of the feedstocks would also need to be determined to ensure an equivalent amount of feed energy value for the new bio-available cattle feed.
Cattle are able to utilize the protein from DDG and DDGS in their diet. The cellulose and hemicellulose are broken down enzymatically in the rumen of the animal as a source of mono- and di-saccharides. The DDGS also contain vitamins and minerals that are beneficial to animals such as cattle.
It is therefore an object of this invention to enable the expansion of ethanol production by corn dry-milling while ensuring adequate feed supply to the cattle market by supplementing the DDG and DDGS produced as a by-product of the dry-milling process with other agricultural processing by-products and pretreated agricultural residues.
The known in the art current method of corn dry-milling is composed of an initial cleaning step by screening (sieving) to remove small broken kernels and impurities and aspiration to remove light impurities for the corn followed by a grinding step utilizing a hammermill or a roller mill. The ground corn is generally heated to 125-150° C. for 10 seconds through a jet cooker at a pressure of about 5.1 bar and then held at 95° C. at ambient pressure for 10 minutes, with 2 times the mass of water added to the ground corn prior to jet cooking, and a high-temperature (from about 80° C. to about 99° C.) α-amylase enzyme (0.01% wt/wt addition) to liquefy the starch to oligosaccharides. The liquefied starch is then cooled to 30° C. and saccharified to glucose by utilizing a glucoamylase (0.01% wt/wt addition) enzyme while simultaneously fermented in a fermentation vessel with Saccharomyces cerevisiae to ethanol at ambient pressure and pH 4-5 for 48 hours. The insoluble pericarp, protein, tip cap, and germ are not separated during the processing and fermentation of the starch. The glucose is fermented primarily by yeast to ethanol with carbon dioxide as a co-product. The theoretical production is 0.51 wt % ethanol and 0.49 wt % carbon dioxide. The glucose concentration is between 200-350 grams per liter in the fermentation broth, which, when fermented, gives a final ethanol concentration of 13-23% on a volume ethanol/volume of fermentation broth basis. The ethanol is distilled at temperatures between 80 and 100° C. and 1.1 bar from the fermentation broth to a final ethanol concentration of 95% and then further dehydrated to 100% by passing the ethanol/water vapors through an adsorption system at 82° C. and at 1.1 bar. The water and solids in the fermentation broth is called stillage and leaves the bottom of the distillation column at ambient pressure and 80° C. The solids remaining in the fermentation broth (pericarp, protein, germ, and tip cap) are separated from the liquid utilizing a centrifuge and optionally dried through a gas-fired rotary drum dryer and agglomerated through a pellet mill or extruder to create distiller's dried grains, which are sold primarily as an animal feed.